Luminaire manufacturers must balance several factors in designing luminaires, in terms of part cost, assembly cost and timing, and the particular application to which a luminaire is directed. Typically, the manufacture and assembly of luminaires, and particularly high-intensity discharge (HID) luminaires, requires a lead time from the point of customer order to the date of delivery due to the many steps involved in the preparing and assembling the subcomponents of the luminaire. Such components that may require such lead time include the electrical assembly. Thus, luminaires do not typically lend themselves to just-in-time manufacturing. Customers of any product demand a timely delivery of goods after ordering, and luminaire buyers are no different. Therefore, manufacturers of lighting systems must often rely upon building up an inventory of parts and subassemblies ahead of time and keeping goods in stock in anticipation of the next order. However, this is a costly proposition which involves having working capital tied up in inventory that is not yet sold to a customer.
Luminaires typically include an optical assembly and an electrical assembly. The optical assembly contains the lamp and the refractor and/or reflector, which produces and directs light at varying degrees. The electrical assembly provides power to the lamp and has a housing which is generally formed of metal and which encloses the electrical circuitry including the ballast. The ballast is used to provide necessary circuit conditions for starting and operating an electric-discharge lamp, such as high intensity electric-discharge lamps of the high pressure sodium, metal halide, or mercury type.
The ballast itself is typically impregnated through a lengthy impregnation dipping process which is complete before the ballast is assembled within an electrical assembly. Impregnation bonds together the laminations which are present in a ballast, reducing the magnetically-induced vibrations which may cause noise. Impregnation also increases the dielectric strength of the insulation system which protects against voltage stress and breakdown from corona. Further, impregnation provides for corrosion resistance and reduces the operating temperature of the ballast.
Moreover, the electrical assembly of a luminaire, and particularly its housing, is sometimes large due to need for relatively large surface area to dissipate ballast heat. The housing size may also be needed in order to provide the clearance necessary for the tools to fit and function to assemble the luminaire and its various subcomponents. Depending on the positioning of the electrical assembly relative to the optical assembly (i.e. above or below), the size of the housing could result in less uplight or downlight, respectively, and thus contribute to an overall less efficient lighting system.
Consequently, the need has developed for an indoor luminaire assembly which permits for a relatively quick and less expensive assembly. The luminaire assembly should not require significant lead time for the manufacture and assembly of its subcomponents and should allow for just-in-time assembly, without the necessity of costly inventory levels. The luminaire should provide for the desired amount of illumination for its application. And the luminaire should include an electrical assembly or housing which is relatively small in order to achieve efficient lighting and not impede the uplight or downlight of the assembly. Further, the electrical assembly should be able to be assembled and finished concurrently with the ballast so as to avoid the lengthy lead time currently required.